Blast Field Contouring Using Upstream Venting

摘要

Modem cannon often employ vents in the tube wall near the muzzle as a lightweightbrake. While all brakes reduce weapon impulse at the expense of increasing blast upstream, this type affords some opportunity to contour the blast field. Normally, the vents are clustered at the muzzle, but calculations indicated that relocating some upstream could reduce blast levels near the breech without compromising weapon impulse or projective velocity. Laboratory experiments using a 20-mm cannon showed a reduction of 4 to 5 dB, as predicted. However, field experiments with a 105-mm cannon showed no beneficial effect of upstream venting. The presence of the ground plane in the latter is believed to be the reason.